1. LESSON 2.2
Writing Formulas
MgCl2

2. Ionic Bonding
An ion is a charged atom caused by the loss or gain of electrons
A positively charged ion has lost electrons
A negatively charged ion has gained electrons
An ionic bond forms from the attraction of positive and negative ions.

3. Ionic Bonding Forces act in all directions
Ionic bonds form between all nearby ions of the opposite charge
The electrical force keeps the atoms close together and bonds them into an electron configuration of a noble gas
Metals usually form a positive ion
Non-metals form a negative ion

4. Example of ionic bonding
Na Cl NaCl
Na Cl salt
Sodium, with one outer electron will become a positive ion when it gives its one electron to chlorine. Chlorine will become a negative ion.

5. Ionic Bonding

6. Properties of Ionic Compounds
Ionic compounds can conduct electricity when melted or dissolved in water
Metal and non-metal bonded together.
They are solid crystals
They have high melting points

7. SUPERSCRIPTS
Superscripts are positive or negative signs written slightly above the elements symbol, which describe the charge of the ion.
EXAMPLES:
Na⁺ shows that sodium has a positive charge
Cl⁻ shows that chlorine has a negative charge

8. SUPERSCRIPTS
When the superscript is ⁺ or ⁻, it is understood to mean 1⁺ or 1⁻.
Because the charges of the sodium and chlorine are opposites, they attract each other.
Superscripts look like: Al+3 C⁴⁻ C⁴⁺ Ca⁺ O-2 Cl-

9. Writing Chemical Formulas for Ionic Bonds
When writing a chemical formula for an ionic bond, the positive ion is listed 1st
The positive ion name does not change.
The negative ion name drops the end of the element name and adds on the suffix “-ide”
Example: Na+ Cl- Sodium Chloride

10. Circle your level of understanding of these concepts:

11. Atoms share electrons
Non-metals usually form bonds with each other by sharing electrons
Covalent bond- a pair of shared electrons between two atoms
These electrons spend time in the outer energy levels of both atoms.

12. COVALENT BONDS
Covalent molecules are neutral because no electrons were gained or lost.
The number of covalent bonds that an atom can form depends on the number of electrons that it has available for sharing

13. Covalent bonds formed with available electrons
Group 14
Group 15
Group 16
Group 17
4 bonds
3 bonds
2 bonds
1 bond

14. Models I I
Lewis structures or
Dot diagrams

15. Models I I I I
Ball and stick model
Electron cloud model

16. Single Covalent Bonds

17. Double Covalent Bonds

18. POLAR MOLECULES
Polar molecule: a molecule formed by sharing electrons that have a slightly positive end and a slightly negative end.
When the atoms in a covalent bond are different the electrons have a stronger attraction to one nucleus than to the other and spend more time near that nucleus.

19. Molecular Structure

20. Circle your level of understanding of these concepts: